Regular Expressions 101

Save & Share

Flavor

  • PCRE2 (PHP >=7.3)
  • PCRE (PHP <7.3)
  • ECMAScript (JavaScript)
  • Python
  • Golang
  • Java 8
  • .NET 7.0 (C#)
  • Rust
  • Regex Flavor Guide

Function

  • Match
  • Substitution
  • List
  • Unit Tests

Tools

Sponsors
There are currently no sponsors. Become a sponsor today!
An explanation of your regex will be automatically generated as you type.
Detailed match information will be displayed here automatically.
  • All Tokens
  • Common Tokens
  • General Tokens
  • Anchors
  • Meta Sequences
  • Quantifiers
  • Group Constructs
  • Character Classes
  • Flags/Modifiers
  • Substitution
  • A single character of: a, b or c
    [abc]
  • A character except: a, b or c
    [^abc]
  • A character in the range: a-z
    [a-z]
  • A character not in the range: a-z
    [^a-z]
  • A character in the range: a-z or A-Z
    [a-zA-Z]
  • Any single character
    .
  • Alternate - match either a or b
    a|b
  • Any whitespace character
    \s
  • Any non-whitespace character
    \S
  • Any digit
    \d
  • Any non-digit
    \D
  • Any word character
    \w
  • Any non-word character
    \W
  • Non-capturing group
    (?:...)
  • Capturing group
    (...)
  • Zero or one of a
    a?
  • Zero or more of a
    a*
  • One or more of a
    a+
  • Exactly 3 of a
    a{3}
  • 3 or more of a
    a{3,}
  • Between 3 and 6 of a
    a{3,6}
  • Start of string
    ^
  • End of string
    $
  • A word boundary
    \b
  • Non-word boundary
    \B

Regular Expression
No Match

/
/
gm

Test String

Code Generator

Language

Generated Code

// include the latest version of the regex crate in your Cargo.toml extern crate regex; use regex::Regex; fn main() { let regex = Regex::new(r"(?m)(?<class>^(?<fully_qualified_class_name>(?<deliniator>(?<!\\)\\(?!\\)(?=(?P>fully_qualified_class_name))){0,1}[A-z_][\w]*)(?=::(?P>method)|$)|^(?<namespace>^(?P>fully_qualified_class_name)*)(?P>deliniator)(?P>fully_qualified_class_name)(?=::(?P>method)|$))(?<scope_resolution_operator>::(?=(?P>method)(?!$)))?(?<method>(?<=::)(?<operation>(?<mutator>[sS]et(?=[A-Z0-1_]|$))|(?<accessor>[gG]et(?=[A-Z0-1_]|$))|(?<condition>[iI]s(?=[A-Z0-1_]|$)|[hH]as(?=[A-Z0-1_]|$)))?_?(?<target>(?<=\w)\w*)|[A-z_]\w*)?$").unwrap(); let string = "/Class and Namespace Capture Nam_e \\_Nam_e Nam_e\\Spac_e /Class Method and Namespace Capture /With Operation and Target Nam_e::set_Singular \\Nam_e\\Spac_e::isSingular \\Nam_e\\Spac_e:: /Class Method and Deep Namespace Capture /Without Operation and Target Nam_e\\Spac_e\\Accessible\\Caller\\Value::setsingular \\Nam_e\\Spac_e\\Accessible\\Caller\\Value::singular /Class Method and Deep Namespace Capture /With Mutator Operation and Target Nam_e\\Spac_e\\Accessible\\Caller\\Value::setSingular /Class Method and Deep Namespace Capture /With Accessor Operation and Target Nam_e\\Spac_e\\Accessible\\Caller\\Value::get_singular /Class Method and Deep Namespace Capture /With Conditional Operation and Target \\Nam_e\\Spac_e\\Accessible\\Caller\\Value::isSingular Nam_e\\Spac_e\\Accessible\\Caller\\Value::has_Singular"; // result will be an iterator over tuples containing the start and end indices for each match in the string let result = regex.captures_iter(string); for mat in result { println!("{:?}", mat); } }

Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for Rust, please visit: https://docs.rs/regex/latest/regex/